It has been well known so far that Long-Term Evolution (LTE) works by being deployed in a licensed carrier. However, as data services increase rapidly, licensed spectrums will be incapable of bearing such a great quantity of data before long. Thus, deploying the LTE in unlicensed spectrums to reduce data traffic in licensed spectrums through the unlicensed spectrums is an important evolution tendency of a further development of the LTE.
Moreover, the unlicensed spectrums have many advantages: it is free or low-cost (it is not needed to buy the unlicensed spectrums, thus, cost on frequency spectrum resources is zero); requirements of the unlicensed spectrums on access is low and access cost of the unlicensed spectrums is low (both individuals and enterprises can participate in deployment and there is no requirements on devices of operators); the unlicensed spectrums are capable of sharing resources (some methods for sharing resources can be considered to improve frequency spectrum efficiency in a case where a plurality of different systems work on the unlicensed spectrums or in a case where different operators of the same system work on the unlicensed spectrums); the unlicensed spectrums are applicable to multiple wireless access technologies (cross-communication standard, poor in cooperative performance and varying in network topology); the unlicensed spectrums have a plenty of wireless access stations (a great number of users, low cooperation and high centralized management cost); and the unlicensed spectrums have a great number of applications (it is mentioned in documents that many services such as Machine to Machine (M2M) and Vehicle to Vehicle (V2V) can work on the unlicensed spectrums).
However, for the unlicensed spectrums, there may be a plurality of systems, for example, WIFI systems, working on the same frequency spectrum. Thus, when a system (e.g. an LTE system) works on an unlicensed spectrum (or called an unlicensed carrier), it is crucial to solve a problem of a coexistence of the system with other systems.
Thus, the problem of the coexistence of the system working on the unlicensed carrier with other systems exists in the related art.